This invention relates to a traction control device (TCS) that is used to prevent rear drive wheels from slipping during braking.
In a conventional rear-wheel traction control device, a proportioning valve (P-valve) is positioned between the rear wheel cylinder and inlet valve, in order to keep the brake pressure of the rear wheels lower than that of the front wheels, thereby stabilizing the vehicle.
A conventional rear-wheel traction control device as described presents the following problems.
1. During traction control, the hydraulic pressure discharged from the pump of the auxiliary hydraulic pressure device is routed through a proportioning valve (P-valve), thus lowering the pressure applied to the wheel cylinder. To compensate for this loss in pressure, the pump must increase the pressure that it discharges. This increases the valve opening pressure of the pressure relief valve, hastens wear-and-tear of the pump, increases the noise level of the motor driving the pump, and creates other problems.
2. Since the proportioning valve is positioned between the rear wheel cylinder and the inlet valve, one P-valve is required for each wheel. This increases space requirements as well as the cost of manufacturing.